Substrate processing using excited species to promote reactions has been a staple of the semiconductor industry for many years. However, with the transition from planar features to 3D features comes a new challenge, conformality. The inventors have observed that conformal processing of high aspect ratio features requires non directional species, which makes direct plasmas with charged species a poor solution. Thus, the inventors believe that radical and excited neutral gas sources will be required to continue processes thermally incompatible materials while also enabling the 3D transition to occur. However, because most radical sources are remote, and therefore removed from the processing regime, and because excited species generally have shorter lifetimes then more stable gas species, techniques for uniform delivery or to create a tunable film thickness across the substrate.
Therefore, the inventors have provided improved methods for forming layers atop a substrate.